1. Field of the Invention
The invention relates to an event information collecting system for a vehicle which stores status information in a storage medium when a problem arises in a vehicle (including vehicle-mounted devices) or when an accident occurs, for example, so that the stored information can help in the determination of the cause of the problem or accident. The invention also relates to such a method for collecting event information on a vehicle.
2. Description of the Related Art
When an event occurs in a vehicle, such as when a problem arises in the vehicle or an accident occurs, information concerning the status of the vehicle, which includes sensor output values and control computation values, is stored in a nonvolatile storage medium, or the like. The information thus stored can help later in the determination of the cause of the problem or cause of the accident at a repair shop, or the like.
The determination of the cause of the problem or accident as described above is called “self diagnosis”, for example. Generally, a control device, such as ECU (electronic control unit), for controlling the vehicle caries out processing for storing information for use in the self diagnosis, concurrently with its original vehicle controls.
The storage medium in which the information is stored in the above manner is called “event data recorder”, for example. According to the laws and regulations of certain countries, it is made mandatory to install an event data recorder on the vehicle.
In this connection, a data recorder (as described in, for example, Japanese Patent Application Publication No. 2008-94252 (JP-A-2008-94252)) detects a driver's operation or operations on the vehicle and the operating state of the vehicle, and determines whether the detected driver's operation(s) and vehicle operating state should be recorded into status recording means, based on at least the driver's operation(s). As one example of the determination as described in the above-identified publication, the driver's operations and vehicle operating state are recorded under conditions that the accelerator pedal is operated and that the foot brake is operated.
In the meantime, the above type of device, which is a vehicle-mounted device, is unlikely to include a dedicated storage medium having an unlimited storage region, and status information of the vehicle is normally written into and stored in a limited storage region while overwriting previously stored information present in the storage region. In the data recorder as described in JP-A-2008-94252, new vehicle status data is recorded into a temporary storage unit while at the same time old vehicle status data is erased or eliminated.
Accordingly, there may arise some occasions where the boundary between the information collected in the present control cycle and the information stored in the last cycle or earlier becomes obscure or unclear. As a result, the past unnecessary information may be recognized as the information collected in the present control cycle, which may result in an erroneous determination made in the later self diagnosis, or may make it impossible to analyze the information.